K. I'm in South Florida where is barely gets under 70 in the "winter", and I run 5w30 in all my cars with no issues.

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I would suppose more open roads in Fl, here in Atlanta we have 285, spaghetti junction and the downtown connector. When you're going through you never know if a 2hr creep along is coming. To top it off the cooling system needs to be in check. But thankfully those extremes have passed the daily commute and from.

The 2nd number represents the viscosity of the oil at near operating temperatu
re. So, a 20w-50 or a 0w-50 is still about a 50 viscosity oil at near engine temp. The first number gives you an idea of how quickly the viscosity will change due to change in temperature. In fact, it's quite likely that a 0W-50 would be thicker in winter weather than a 10W-30 at cranking temperatures, for example. The critically important part of thinner oils in winter has to do with how long it takes, or how difficult it is to get the oil circulating and to get the oil pressure to rise throughout the engine. It's just not as bad as it used to be.

Thus, how hot it gets in the summer really doesn't make a difference. More concerning is how cold it gets in the winter.

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I put in a harden oil pump shaft along with a high volume oil pump and it seems to have matched nicely with the 20w-50. I was scared of the winter cause I just wasn't sure but it does real well all together.

I would suppose more open roads in Fl, here in Atlanta we have 285, spaghetti junction and the downtown connector. When you're going through you never know if a 2hr creep along is coming. To top it off the cooling system needs to be in check. But thankfully those extremes have passed the daily commute and from.

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I've been to ATL many times. Could never live there as the commute from the Dunwoody/Buckhead area to downtown and back each day takes over an hour and I would end up killing someone.. lol

However, I take it you've never been to S Florida. The commute on 95 or going to a major city like West Palm, Ft. Lauderdale or Miami rivals Atlanta and it's HOT here. Like 95-100 degrees with 90% humidity. That plays havoc on a motor and cooling system.

Glad what you have is working for you but like I said, I've run 5w30 dyno and synthetic oils in my cars for decades here with no problems. I bet if you switch to either a 10W or 5W 30 you'll get better MPG and pick up a few HP.

I've been to ATL many times. Could never live there as the commute from the Dunwoody/Buckhead area to downtown and back each day takes over an hour and I would end up killing someone.. lol

However, I take it you've never been to S Florida. The commute on 95 or going to a major city like West Palm, Ft. Lauderdale or Miami rivals Atlanta and it's HOT here. Like 95-100 degrees with 90% humidity. That plays havoc on a motor and cooling system.

Glad what you have is working for you but like I said, I've run 5w30 dyno and synthetic oils in my cars for decades here with no problems. I bet if you switch to either a 10W or 5W 30 you'll get better MPG and pick up a few HP.

Like I always say, that's why Baskin Robbins makes 31 flavors..

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I play in a baseball tourney near West Palm every November, but that's flying in riding with peeps from the airport, but they've always been at odd hours. The pan handle is where I've always went otherwise, Destin Fl, PC Beach Fl. They always had those parallel roads that are always open. I'm close to an oil change but with my high volume oil pump, I'm scared it would be too easy for it. I have heard bad things with those on stock motors and light oil. Would certainly like more HP's & MPG's

The 2nd number represents the viscosity of the oil at near operating temperature. So, a 20w-50 or a 0w-50 is still about a 50 viscosity oil at near engine temp. The first number gives you an idea of how quickly the viscosity will change due to change in temperature. In fact, it's quite likely that a 0W-50 would be thicker in winter weather than a 10W-30 at cranking temperatures, for example. The critically important part of thinner oils in winter has to do with how long it takes, or how difficult it is to get the oil circulating and to get the oil pressure to rise throughout the engine. It's just not as bad as it used to be.

Thus, how hot it gets in the summer really doesn't make a difference. More concerning is how cold it gets in the winter.

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The "w" number shows what viscosity the oil behaves like in "winter" temperatures. A 10w-50, 15w-50, 20w-50, all behave like 50-weights at 100C. But they behave like 10, 15, 0r 20-weight oils at sub-freezing temps. Still very thick, because it's so cold, yet thinner than a 50 would be at the same very cold temperature.

Mod Dude

MFE, I'm well aware. The point I was making was that contrary to the common misunderstanding, a lower "W" multigrade oil is not going to become thinner at lower temperatures.

A 10w-50, 15w-50, 20w-50, all behave like 50-weights at 100C.

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yes.

But they behave like 10, 15, 0r 20-weight oils at sub-freezing temps.

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Kind of...but not exactly

I hope this doesn't offend you, but that's a very simplistic, and sometimes incorrect, interpretation of a very complex subject. I'll show an example of why, and don't just consider weight because there are other standards that must be met to classify the grade of the oil. If it passes the viscosity/temperature standard, it may still get bumped into another grade because it fails a sheer standard for a given grade.

Under our normal operating conditions, 0W-40 isn't less than 5W-30 at startup. In other words, it is not thinner. Mobile 1's 0W-40 will actually have more resistance to flow in a cold motor than its 5W-30.

At 40* celsius (104*F), which is the lowest temp for which their viscosity is listed, the 5W-30 is thinner (61.7 cSt vs. 75 cSt). At operating temperature, as anyone would expect, the 5W-30 is also thinner (11cST vs. 13.5cSt).

It's broken down in 5* C increments, but for the interest of brevity, I'm not going to list the results of every cell. If you want that level of detail, just enter the data from the product sheet into the flash app at the link above.

So, the results indicate that the 5W-30 oil is thinner than the 0W-40 at any temperature higher than -35*C (-31*F). At that temperature and colder, 0W-40 is finally thinner than 5W-30. Now, I it gets cold here in Germany, but I'm certain I have never started my corvette at or below this temperature.

This shouldn't be a surprise since you're comparing a 40 weight oil to a 30 weight oil. Now, for what it's worth, I believe from a technical perspective that 5W-30 is the better selection in general at the kind of "freezing" temperatures that I will experience, but it's precisely because the oil is thinner and will flow more easily than the heavier "0W" oil, which I think is contrary to your reasoning. Seems like someone (not you) might argue that the thicker oil offers more protection at low temperature or something, but as you can see above, both oils are much thicker at low temperatures than they are at operating temperatures. So, the oils are obviously more than thick enough to provide adequate protection. More important is how quickly each oil will flow through the lubrication system and build pressure.

In the older days, oil pumps couldn't generate the pressure to move the oil from the pan when it was too cold. That's not going to happen with either of these oils unless you're in antarctica. So, the entire argument is moot. Bottom line: these oils are very close to each other in cold weather performance.

In a racing application, we'd be talking about other things (shear strength, new operating temps, high temp areas of the motor, etc...). Then the advantages of a 40 weight oil might really begin to be significant. But even cruising on the autobahn at 200 kph (124mph) for several hours is not going to begin to push the car like 2 back to back hotlaps at the nurburgring.

Anyway, the point is, there's a lot of things that go into grade. I know you were trying to kind of fill me in on the meaning of the W, but I was aware of the "winter" rating, and didn't want to state something incorrect while at the same time, I wasn't originally planning on giving a class.

I wasn't trying to fill you in on the meaning of the W, and I didn't set out to post a technical treatise on viscosities. Your explanation regarding how quickly the viscosity would change left me a little....cold.

great info Chris...i like RP and so far my 333 stroker likes it too its been swimming in two quarts of 20/50 and three 10/30 each oil change for 23k miles now, valvetrain sounds quieter and smoother with two 20/50 mixed in i dont mind loses a hp or two for a happy engine

great info Chris...i like RP and so far my 333 stroker likes it too its been swimming in two quarts of 20/50 and three 10/30 each oil change for 23k miles now, valvetrain sounds quieter and smoother with two 20/50 mixed in i dont mind loses a hp or two for a happy engine